Button cell having winding electrode and method for the production thereof

ABSTRACT

A method for producing a button cell includes providing a metal cell cup, providing a metal cell top, and providing a first electrode and a second electrode. The first electrode includes a first current collector partially coated with a first active electrode material and having an active material-free region. The second electrode includes a second current collector partially coated with a second active electrode material and having an active material-free region. The method further includes attaching a first metal foil conductor to the active material-free region of the first current collector, attaching a second metal foil conductor to the active material-free region of the second current collector, and forming a cylindrical electrode winding by winding, in a spiral, an electrode assembly. The first and second metal foil conductors extend out of the cylindrical electrode winding from first and second end faces of the cylindrical electrode winding.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a divisional of U.S. application Ser. No.17/465,940, filed Sep. 3, 2021, which is a divisional of U.S.application Ser. No. 17/238,329, filed Apr. 23, 2021 (now U.S. Pat. No.11,158,896), which is a divisional of U.S. application Ser. No.17/173,222 (now U.S. Pat. No. 11,024,907), filed Feb. 11, 2021, which isa divisional of U.S. application Ser. No. 15/699,435, filed Sep. 8, 2017(now U.S. Pat. No. 11,024,904), which is a divisional of U.S.application Ser. No. 13/378,117 filed Dec. 14, 2011 (now U.S. Pat. No.9,799,858), which is a § 371 of International Application No.PCT/EP2010/058637, with an international filing date of Jun. 18, 2010(WO 2010/146154 A2, published Dec. 23, 2010), which is based on GermanPatent Application Nos. 10 2009 030 359.6, filed Jun. 18, 2009, and 102009 060 800.1, filed Dec. 31, 2009, all of which applications arehereby incorporated by reference herein.

FIELD

This disclosure relates to button cells having a housing consisting oftwo metal housing halves, which contains a wound electrode separatorassembly, and to a method for its production.

BACKGROUND

Button cells conventionally comprise a housing consisting of two housinghalves: a cell cup and a cell top. These may, for example, be producedas stamped parts from nickel-plated deep-drawn sheet metal. Usually, thecell cup is positively poled and the housing top negatively poled. Thehousing may contain a very wide variety of electrochemical systems, forexample, zinc/MnO₂, primary and secondary lithium systems, or secondarysystems such as nickel/cadmium or nickel/metal hydride.

The liquid-tight closure of button cells is conventionally carried outby crimping the edge of the cell cup over the edge of the cell top, incombination with a plastic ring which is arranged between the cell cupand the cell top and is used simultaneously as a sealing element and forelectrical insulation of the cell cup and the cell top. Such buttoncells are described, for example, in DE 31 13 309.

As an alternative, however, it is also possible to manufacture buttoncells in which the cell cup and the cell top are held together in theaxial direction exclusively by a force-fit connection, and whichcorrespondingly do not have a crimped cup edge. Such button cells and amethod for their production are described in DE 10 2009 017 514.8.Regardless of the various advantages which such button cells withoutcrimping may present, they nevertheless cannot withstand such highstresses in the axial direction as comparable button cells with acrimped cup edge, especially as regards axial mechanical loads whichoriginate from inside the button cell. For example, the electrodes ofrechargeable lithium ion systems are constantly subjected to volumechanges during charging and discharging processes. In button cellswithout crimping, the axial forces occurring in this case can naturallycause leaks more easily compared with button cells with crimping.

A solution to this problem may be found in DE 10 2009 030 359.6 and DE10 2009 008 859.8. Inter alia, references may be found therein to buttoncells comprising a housing having a plane bottom region and a plane topregion parallel thereto, an assembly consisting of flat electrode layersand separator layers in the form of a preferably spiral-shaped electrodewinding being arranged in the housing in such a way that the end sidesof the winding face in the direction of the plane bottom region and theplane top region. The electrode layers of the winding are thus orientedessentially orthogonally to the plane bottom and top regions of thehousing. As a result, radial forces such as occur during theaforementioned charging and discharging processes of lithium ion systemscan in principle be absorbed better than in of conventional lithium ionbutton cells, in which electrode layers are arranged stacked in parallelalignment with the plane bottom and top regions.

Windings consisting of flat electrode layers and separator layers can beproduced quite straightforwardly using known methods (see, for example,DE 36 38 793) by the electrodes being applied, in particular laminated,particularly in the form of strips, flat onto a separator provided as anendless band. The assembly consisting of the electrodes and separatorsis generally wound on a so-called “winding mandrel.” After the windinghas been removed from the winding mandrel, an axial cavity is left atthe center of the winding, the effect of which is that the winding maypossibly expand into this cavity. This, however, can sometimes lead toproblems in the electrical contact of the electrodes with the metalhousing halves.

It could therefore be helpful to provide a button cell in which theaforementioned problems do not occur, or only occur to a greatly reducedextent.

SUMMARY

The present invention provides a method for producing a button cell. Themethod includes providing a metal cell cup, providing a metal cell top,and providing a first electrode and a second electrode. The firstelectrode includes a first current collector partially coated with afirst active electrode material and having an active material-freeregion. The second electrode includes a second current collectorpartially coated with a second active electrode material and having anactive material-free region. The method further includes attaching afirst metal foil conductor to the active material-free region of thefirst current collector, attaching a second metal foil conductor to theactive material-free region of the second current collector, and forminga cylindrical electrode winding by winding, in a spiral, an electrodeassembly. The electrode assembly includes he first electrode with thefirst metal foil conductor attached thereto, a first separator layer,the second electrode with the second metal foil conductor attachedthereto, and a second separator layer. The first metal foil conductorextends out of the cylindrical electrode winding from a first end faceof the cylindrical electrode winding, and the second metal foilconductor extends out of the cylindrical electrode winding from a secondend face of the cylindrical electrode winding. The method additionallyincludes folding the first metal foil conductor to bear flat on thefirst end face of the cylindrical electrode winding, folding the secondmetal foil conductor to bear flat on the second end face of thecylindrical electrode winding, and welding the first metal foilconductor to a first housing part and welding the second metal foilconductor to a second housing part. The first housing part is one of themetal cell cup or the metal cell top and the second housing part is theother of the metal cell cup or the metal cell top. The method alsoincludes assembling the metal cell cup and the metal cell top to form ahousing in which the cylindrical electrode winding is disposed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B schematically show a cross section of a preferredexample of a button cell 100.

FIGS. 2A to 2C schematically show selected assembly steps of the buttoncell of FIG. 1 .

FIGS. 3A and 3B schematically show selected views of windings of thebutton cell.

FIGS. 4A and 4B schematically show two different welds.

FIG. 5 shows microphotographs of a weld from top and cross-sectionalviews.

DETAILED DESCRIPTION

My button cell always comprises two metal housing halves separated fromone another by an electrically insulating seal and forming a housinghaving a plane bottom region and a plane top region parallel thereto. Asmentioned above, the two housing halves are generally a so-called“housing cup” and a “housing top.” In particular, nickel-plated steel orsheet metal are preferred as the material for the housing halves.Trimetals, in particular, are furthermore suitable as the metallicmaterial, for example, ones comprising the sequence nickel, steel (orstainless steel) and copper (in which case the nickel layer preferablyforms the outer side of the button cell housing and the copper layerpreferably forms the inner side).

As the seal, it is, for example, possible to use an injection-moldedseal or a film seal. The latter are described, for example, in DE 196 47593.

At least one positive electrode and at least one negative electrode arearranged inside the housing, specifically each in the form of flatelectrode layers. The electrodes are preferably connected to one anotherby at least one flat separator. The electrodes are preferably laminatedor adhesively bonded onto this separator. The electrodes and theseparator generally each have a thickness only in the μm range. A porousplastic film is generally used as the separator.

This assembly is provided in the form of a winding, particularly in theform of a spiral-shaped winding, in the housing of a button cell, thewinding being arranged such that its end sides face in the direction ofthe plane bottom region and the plane top region of the housing. Fullreference is hereby made to the description of such windings, and buttoncells comprising such windings, in DE 10 2009 030 359.6 and DE 10 2009008 859.8 already mentioned above. All the preferred forms described inthose applications are also intended to apply for the button celldescribed here and the electrode winding described here.

Besides the housing halves and the electrode separator assembly, mybutton cell always also comprises metal conductors which electricallyconnect the at least one positive electrode and/or the at least onenegative electrode respectively to one of the housing halves. Theconductor or conductors connected to the at least one positive electrodepreferably consist of aluminum. The conductors connected to the at leastone negative electrode preferably consist of nickel or copper.

On the electrode side, the conductors are preferably connected tocurrent collectors. The latter are generally metal foils or meshesconventionally coated on both sides with active electrode material.These current collectors preferably consist of aluminum on the side ofthe positive electrode, and preferably nickel or copper on the side ofthe negative electrode. The foils or meshes have, in particular,thicknesses of between 1 μm and 100 μm. The connecting of the conductorsto the current collectors is preferably carried out by welding.

Particularly in respect of preferred forms of the electrode separatorassembly arranged in my button cell, reference is made to DE 10 2009 030359.6 and DE 10 2009 008 859.8. These disclose in particular preferredlayer sequences and layer thicknesses for electrodes and separators, forexample, an assembly comprising the layer sequence:

-   -   negative electrode/separator/positive electrode/separator    -    or    -   positive electrode/separator/negative electrode/separator.

Assemblies comprising the layer sequences:

-   -   negative electrode/separator/positive        electrode/separator/negative electrode    -    or    -   positive electrode/separator/negative        electrode/separator/positive electrode        may also be preferred. The assembly therefore comprises more        than one positive electrode and/or more than one negative        electrode.

Particularly preferably, at least one of the electrodes of a button cellis a lithium intercalation electrode. The button cell is preferably alithium ion battery, in particular a secondary lithium ion battery.

My button cell is distinguished particularly in that at least one of theconductors is welded to the respective housing half, preferably both theconductor connected to the at least one positive electrode and theconductor connected to the at least one negative electrode.

As has already been mentioned above, particularly in lithium ion buttoncells, the electrodes are subject to volume changes during acharging-discharging cycle, as a result of which contact problems mayarise between the conductors and the housing halves. Such contactproblems no longer apply when the conductors are welded to therespective housing halves.

Particularly preferably, the conductor or conductors are welded onto theinner side of the housing in the plane bottom region or the plane topregion, respectively, of the housing. For this purpose, according toconventional methods the welding process must be carried out before thehousing is assembled, which is very difficult to achieve in terms ofproduction technology. Welded connections have therefore been regardedas highly disadvantageous for bonding the conductors to the inner sideof the housing halves. By virtue of my method as described in moredetail below, however, a solution can be provided which also has greatadvantages in terms of production technology.

By the welding, the at least one positive electrode and/or the at leastone negative electrode are thus connected by one or more conductorsdirectly to the plane bottom region or to the plane top region of thehousing of a button cell, the housing top generally being polednegatively and the housing cup positively.

The button cell is preferably a conventional button cell having acircular plane bottom region and a circular plane top region. In somecases, the button cell may nevertheless have an oval configuration. Itis, however, important that the ratio of height to diameter ispreferably always less than 1. Particularly preferably, it is 0.1 to0.9, in particular 0.15 to 0.7. The height is intended to mean theshortest distance between the plane bottom region and the plane topregion parallel thereto. The diameter means the maximum distance betweentwo points on the lateral region of the button cell.

Preferably, the conductors of a button cell are flat conductors, inparticular metal foils, particularly preferably rectangular, strip- orband-shaped metal foils. The foils preferably have thicknesses of 5 μmto 100 μm.

The conductors are preferably separate components bonded, in particularwelded, to the electrodes, in particular to the current collectors inthe electrodes. As an alternative, however, the conductors may also beuncoated sections of a current collector (sections which are free ofactive electrode material), in particular the uncoated ends of such acurrent collector. By bending these uncoated sections, in particularthese uncoated ends, for example, through 90°, these ends can beconnected to the bottom or top region of a button cell. There, theconnecting is preferably carried out by welding.

Preferably, at least one subsection of the conductor or conductors bearsflat on the inner side of the housing half or halves in the bottomand/or top region of the housing, in particular when the conductors areflat conductors such as foils. Such conductors may form a flat layerbetween the inner side of the housing halves and an end side of theelectrode winding, and therefore a large-area electrical contact withthe housing.

Since in principle both positive and negative electrodes may be exposedon the end sides of the electrode winding, however, it is necessary toavoid a short circuit between the electrodes. Particularly preferably,my button cell therefore comprises at least one separate insulatingmeans which prevents direct electrical contact between the end sides ofthe winding and the conductors, in particular a subsection of theconductor or conductors which bears flat on the inner side of thehousing halves. Such an insulating means may, for example, be a film,for example, a plastic adhesive film, by which the side of the conductoror conductors remote from the inner side of the button cell housing iscovered.

The electrode winding of a button cell may be produced by known methods,for example, the method described in DE 36 38 793, according to whichelectrodes and separators are wound on a winding mandrel. After thewinding has been removed from the winding mandrel, there may be an axialcavity at the center of the winding, preferably an essentiallycylindrical axial cavity. In the housing of my button cell, such acavity is delimited laterally by the winding and on the end sides by thebottom or top region of the housing, respectively, or at least by asubregion thereof. Particularly preferably, the at least one conductoris welded to one housing half or the housing halves in one of thesesubregions.

The axial cavity may optionally contain a winding core, which canprevent the winding from expanding uncontrolledly into the cavity.

The button cell is in particular a button cell without crimping, as isdescribed in DE 10 2009 017 514.8. Accordingly, there is preferably anexclusively force-fit connection between the housing halves. The but-toncell thus does not have a crimped cup edge, as is always the case withbutton cells known from the prior art. The button cell is closed withoutcrimping. The content of DE 10 2009 017 514.8 is also fully incorporatedherein by reference. All the preferred forms described in thatapplication is also intended to apply for the button cell described hereand its housing.

As already mentioned above, welding of conductors to the inner side ofbutton cell housings is very elaborate in terms of productiontechnology. I overcome this problem with my method of producing buttoncells, which always comprises at least the following steps:

-   -   (a) providing a first and a second metal housing half        (preferably a cell cup, and a cell top),    -   (b) placing an electrode separator assembly comprising a        positive electrode and a negative electrode in one of the        housing halves (preferably into the cell top), a metal conductor        being bonded to at least one of the electrodes (preferably to        all the electrodes),    -   (c) assembling the two housing halves (preferably by inserting        the cell top into the cell cup), optionally with the provision        of separate steps for sealing the housing (for example, fitting        a seal) and    -   (d) welding at least one of the conductors to the inner side of        one of the metal housing halves.

The components used in the method such as the housing halves, theconductors and the electrode separator assembly, have already beendescribed above. Reference is hereby made to the corresponding remarks.

The method is distinguished in particular in that step (d) is carriedout after step (c). This means that the at least one conductor is weldedto the inner side of the housing when the housing is closed. The weldingmust correspondingly be carried out from the outside through the housingwall of one or both housing halves.

Accordingly, I provide button cells which have weld beads and/or weldspots that pass through the housing, in particular starting from itsouter side.

Particularly preferably, the conductor or conductors and the button cellhousing are connected to one another by one or more spot-like and/orlinear welded connections.

Welding the conductors and the housing is preferably carried out by alaser. Its operating parameters must be adapted as accurately aspossible to the thickness of the housing. The power may, for example, bemodulated by varying the pulse frequency. Lastly, the laser shouldmerely ensure welding of the housing and conductors while othercomponents such as the electrode winding should as far as possible notbe damaged.

Suitable lasers are, for example, commercially available fiber lasers,i.e., solid-state lasers, in which the doped core of a glass fiber formsthe active medium. The most common dopant for the laser-active fibercore is erbium. For high-power applications as in the present case,however, ytterbium and neodymium are more preferred.

Irrespective of the fact that such lasers can be adapted very finely tothe respective housing thickness and conductor dimension, it isnevertheless possible that in certain cases the intensity of the laserwill be selected to be too strong and the laser will penetrate throughthe housing wall and the conductor. For this reason, welding theconductors to the housing is particularly preferably carried out in thesubregion of the bottom or top region, which delimits the axial cavityat the center of the winding on the end side. If a laser beam penetratesthrough the housing in this region, the winding cannot be damaged.Instead, the laser beam will be absorbed by the housing half lyingopposite or by a winding core optionally arranged inside the cavity.

If possible, the conductors to be welded should bear as flatly aspossible on the inner side of the housing. This may, for example, beensured by fixing the conductors flat by an adhesive tape onto or at theend sides of an electrode winding, before the latter is inserted intothe housing.

The aforementioned advantages, and further advantages thereof, are inparticular also revealed by the description which now follows of thedrawings. In this context, the individual features may be implementedseparately or in combination with one another. The examples describedmerely serve for explanation and better understanding, and are in no wayto be interpreted as restrictive.

Button cell 100 comprises two metal housing halves: a metal cup part 101and a metal top part 102. With a seal 103 lying between them, the twoparts are connected together in a leaktight fashion. Together, they forma housing having a plane bottom region 104 and a plane top region 105parallel thereto. In the functional state, these two plane regions 104and 105 form the poles of the button cell 100, from which current can bedrawn by a load. The cell top 102 is inserted into the cell cup 101 sothat the lateral surface regions of the cell top and the cell cupoverlap, the internal radius of the cell cup 101 in the overlap region106 being essentially constant in the direction of the rim 107. The edgeof the cell 101 is thus not crimped. The button cell 100 is therefore anuncrimped button cell.

An assembly 108 of strip-shaped electrodes and strip-shaped separatorsis arranged inside the electrode. The assembly 108 is provided in theform of a spiral-shaped winding, the end sides of which face in thedirection of the plane bottom region 104 and the plane top region 105parallel thereto. The assembly is wound on the winding core 109 at thecenter of the button cell 100. The winding core is a hollow plasticcylinder, which partially fills an axial cavity at the center of thewinding. The cavity itself is delimited laterally by the winding andupward and downward by corresponding circular sections of the plane cupand top regions of the button cell housing. Metal foils 110 and 111,which act as conductors and are connected to the electrodes, bear flaton these regions. These conductors are shielded from the end sides ofthe winding by the insulating elements 112 and 113. The latter are thinplastic films. The wall thickness of the housing in the region of theplane bottom or top region is generally 30 μm to 400 μm. The thicknessof the metal foils 110 and 111 acting as conductors generally lies 5 μmto 100 μm.

Welding of the metal foils 110 and 111, acting as conductors, to therespective housing half, which is preferably done by the schematicallyrepresented laser 114, is preferably carried out in that subregion ofthe bottom region or of the top region of the button cell housing whichdelimits the axial cavity at the center of the winding on the end side.This creates a weld bead 115 which passes fully through the housing ofthe button cell 100 from the outside inward, and by which the internallylying metal foils 110 and 111 acting as conductors are firmly connectedto the inner side of the housing. This can be seen clearly in the detailenlargement (FIG. 1B).

FIG. 2A to FIG. 2C represent some important steps in the production ofan electrode winding, which is suitable in particular for button cells(for example, as represented in FIG. 1 ). Thus, FIG. 2A shows segmentedcollector foils 201 and 202 coated with active electrode material, towhich conductor strips 203 and 204 offset at an angle of 90° areattached by welding. The conductor 204 on the anode side consists ofnickel or copper, and the conductor 203 on the cathode side of aluminum.The conductors 203 and 204 are respectively applied in a material-freeregion (205, 206) of the collector foils 201 and 202. Elsewhere, theyare coated with active material on both sides. The connection betweenthe collector foils 201 and 202 and the conductors may, for example, beproduced by welding in the region 211.

FIG. 2B and FIG. 2C represent the way in which the rear sides of theconductors 203 and 204 are adhesively bonded using an insulating tape207 and 208 (for example, made of KAPTON or polypropylene) (Step 2).This insulating tape is subsequently intended to function as aninsulating element, which is meant to prevent direct electrical contactbetween the conductors 203 and 204 and the end sides of the electrodewinding which is to be produced. The conductors 203 and 204 are fixed onthe front in a further step (Step 3) with further adhesive strips 209and 210. The region 211 is bonded over in this case.

The conductor position in a winding of electrode foils obtainedaccording to FIG. 2A to FIG. 2C can be seen clearly in FIG. 3A. Twodifferent perspective representations of the same winding are shown(left and right). The conductor 301 (which corresponds to the conductor204 in FIG. 2 ) and the conductor 302 (which corresponds to theconductor 203 in FIG. 2 ) are themselves aligned axially at a 90° angleto the winding direction and by folding down by 90° bear flat on the endsides 303 and 304 of the electrode winding. The insulating elements 305and 306 (which correspond to the insulating tapes 207 and 208 in FIG. 2) prevent direct electrical contact between the conductors 301 and 302and the end sides 303 and 304 of the electrode winding represented. Theouter side of the winding is protected by the insulating film 307.Ideally, the conductors 301 and 302 overlap with the openings of theaxial cavity 308 on the end sides so that welding to the button cellhousing can be carried out in this region. This can be seen clearly inFIG. 3B, as can the winding core 309 which fills the axial cavity 308.

FIGS. 4A and 4B show possible welding variants. For example, it ispossible to configure the weld bead as a minus sign 401 or a plus sign402 (see the respective enlarged representations on the right) so as toindicate the polarity of the respective housing half at the same time.The plus sign 402 is preferably applied on the lower side 404 of abutton cell, and the minus sign on the upper side 403.

FIG. 5 shows an enlarged representation of a cross section through ahousing half 500 of a button cell. The stainless steel cup wall 501, thealuminum conductor 502 bearing flat underneath and an insulating tape503 of KAPTON film arranged below can be seen. The weld beads 504 and505, which extend from the outer side of the housing inward as far asthe insulating tape 503 of KAPTON film can be seen clearly. The top leftimage is a plan view of the cutaway plane bottom region of the housinghalf 500. The housing half 500 and the conductor 502 have been weldedusing an ytterbium-doped fiber laser of the YLR-400-AC type(manufacturing company IPG Photonics Corporation, USA). The intensity ofthe laser was in this case adjusted so that the insulating tape 503 wasnot penetrated.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive. Itwill be understood that changes and modifications may be made by thoseof ordinary skill within the scope of the following claims. Inparticular, the present invention covers further embodiments with anycombination of features from different embodiments described above andbelow. Additionally, statements made herein characterizing the inventionrefer to an embodiment of the invention and not necessarily allembodiments.

The terms used in the claims should be construed to have the broadestreasonable interpretation consistent with the foregoing description. Forexample, the use of the article “a” or “the” in introducing an elementshould not be interpreted as being exclusive of a plurality of elements.Likewise, the recitation of “or” should be interpreted as beinginclusive, such that the recitation of “A or B” is not exclusive of “Aand B,” unless it is clear from the context or the foregoing descriptionthat only one of A and B is intended. Further, the recitation of “atleast one of A, B and C” should be interpreted as one or more of a groupof elements consisting of A, B and C, and should not be interpreted asrequiring at least one of each of the listed elements A, B and C,regardless of whether A, B and C are related as categories or otherwise.Moreover, the recitation of “A, B and/or C” or “at least one of A, B orC” should be interpreted as including any singular entity from thelisted elements, e.g., A, any subset from the listed elements, e.g., Aand B, or the entire list of elements A, B and C.

What is claimed is:
 1. A method for producing a button cell, the methodcomprising: providing a metal cell cup; providing a metal cell top;providing a first electrode, the first electrode including a firstcurrent collector partially coated with a first active electrodematerial and having an active material-free region; attaching a firstmetal foil conductor to the active material-free region of the firstcurrent collector; providing a second electrode, the second electrodeincluding a second current collector partially coated with a secondactive electrode material and having an active material-free region;attaching a second metal foil conductor to the active material-freeregion of the second current collector; forming a cylindrical electrodewinding by winding, in a spiral, an electrode assembly, the electrodeassembly including: the first electrode with the first metal foilconductor attached thereto, a first separator layer, the secondelectrode with the second metal foil conductor attached thereto, and asecond separator layer, wherein the first metal foil conductor extendsout of the cylindrical electrode winding from a first end face of thecylindrical electrode winding and the second metal foil conductorextends out of the cylindrical electrode winding from a second end faceof the cylindrical electrode winding; folding the first metal foilconductor to bear flat on the first end face of the cylindricalelectrode winding and folding the second metal foil conductor to bearflat on the second end face of the cylindrical electrode winding;welding the first metal foil conductor to a first housing part andwelding the second metal foil conductor to a second housing part,wherein the first housing part is one of the metal cell cup or the metalcell top and the second housing part is the other of the metal cell cupor the metal cell top; and assembling the metal cell cup and the metalcell top to form a housing in which the cylindrical electrode winding isdisposed.
 2. The method of claim 1, wherein attaching the first metalfoil conductor to the active material-free region of the first currentcollector is performed by welding a first portion of the first metalfoil conductor to the active material-free region of the first currentcollector.
 3. The method of claim 2, further comprising, after attachingthe first metal foil conductor to the active material-free region of thefirst current collector but before forming the cylindrical electrodewinding: adhesively bonding a first insulating tape to a rear side ofthe first metal foil conductor along a second portion of the first metalfoil conductor, and wherein the folding the first metal foil conductorto bear flat on the first end face of the cylindrical electrode windingcomprises folding the first metal foil conductor towards the rear sideof the first metal foil conductor such that the second portion of thefirst metal foil conductor bears flat on the first end face of thecylindrical electrode winding with the first insulating tape disposedbetween the second portion of the first metal foil conductor and thefirst end face of the cylindrical electrode winding.
 4. The method ofclaim 3, further comprising adhesively bonding the first insulating tapeto (i) a rear side of the first metal foil conductor along the firstportion of the first metal foil conductor or (ii) a portion of theactive material-free region of the first current collector to which thefirst portion of the first metal foil conductor is welded.
 5. The methodof claim 4, further comprising bonding a first adhesive strip to (i) afront side of the first metal foil conductor along the first portion ofthe first metal foil conductor or (ii) a portion of the activematerial-free region of the first current collector to which the firstportion of the first metal foil conductor is welded.
 6. The method ofclaim 5, wherein attaching the second metal foil conductor to the activematerial-free region of the second current collector is performed bywelding a first portion of the second metal foil conductor to the activematerial-free region of the second current collector.
 7. The method ofclaim 6, further comprising, after attaching the second metal foilconductor to the active material-free region of the second currentcollector but before forming the cylindrical electrode winding:adhesively bonding a second insulating tape to a rear side of the secondmetal foil conductor along a second portion of the second metal foilconductor, and wherein the folding the second metal foil conductor tobear flat on the second end face of the cylindrical electrode windingcomprises folding the second metal foil conductor towards the rear sideof the second metal foil conductor such that the second portion of thesecond metal foil conductor bears flat on the second end face of thecylindrical electrode winding with the second insulating tape disposedbetween the second portion of the second metal foil conductor and thesecond end face of the cylindrical electrode winding.
 8. The method ofclaim 7, further comprising adhesively bonding the second insulatingtape to (i) a rear side of the second metal foil conductor along thefirst portion of the second metal foil conductor or (ii) a portion ofthe active material-free region of the second current collector to whichthe first portion of the second metal foil conductor is welded.
 9. Themethod of claim 8, further comprising bonding a second adhesive strip to(i) a front side of the second metal foil conductor along the firstportion of the second metal foil conductor or (ii) a portion of theactive material-free region of the second current collector to which thefirst portion of the second metal foil conductor is welded.
 10. Themethod of claim 1, wherein the welding the first metal foil conductor tothe first housing part and/or the welding the second metal foilconductor to the second housing part is performed after the assemblingthe metal cell cup and the metal cell top to form the housing.
 11. Themethod of claim 10, wherein the welding the first metal foil conductorto the first housing part and/or the welding the second metal foilconductor to the second housing part is performed via laser welding. 12.The method of claim 10, wherein the first metal foil conductor is weldedto the first housing part via at least one weld spot and/or the secondmetal foil conductor is welded to the second housing part via at leastone weld spot.
 13. The method of claim 1, further comprising forming theelectrode assembly by laminating and/or adhesively bonding the firstelectrode to the first separator layer, the first separator layer to thesecond electrode, and the second electrode to the second separatorlayer.
 14. The method of claim 13, wherein the winding the electrodeassembly in a spiral is performed by winding the electrode assembly on awinding mandrel.
 15. The method of claim 14, wherein the forming theelectrode assembly winding comprising removing the spiral woundelectrode assembly from the winding mandrel, an axial cavity beingprovided at the center of the winding.
 16. The method of claim 15,wherein a winding core is provided in the axial cavity.
 17. The methodof claim 1, wherein the metal cell cup includes a circular plane regionconnected to a cell cup lateral surface region, and wherein the metalcell top includes a circular top region connected to a cell top lateralsurface region.
 18. The method of claim 17, wherein assembling the metalcell cup and the metal cell top to form the housing comprises insertingthe cell top into the cell cup so that the lateral surface regions ofthe cell top and the cell cup overlap in an overlap region.
 19. Themethod of claim 18, wherein, after assembling the metal cell cup and themetal cell top to form the housing, an internal radius of the lateralsurface region of the cell cup is constant in the overlap region. 20.The method of claim 19, wherein a seal is disposed between the lateralsurface regions of the cell top and the cell cup in the overlap regionto provide a force-fit connection between the metal cell cup and themetal cell top.